Carruthers D M, Arrol H P, Bacon P A, Young S P
Department of Rheumatology, University of Birmingham, UK.
Arthritis Rheum. 2000 Jun;43(6):1257-65. doi: 10.1002/1529-0131(200006)43:6<1257::AID-ANR8>3.0.CO;2-Q.
Peripheral blood (PB) T cells from rheumatoid arthritis (RA) patients proliferate poorly to mitogen, a change that is related to decreased intracellular Ca2+ ([Ca2+]i) signaling after T cell receptor (TCR) stimulation. We hypothesized that this was, in part, due to the effect of mediators of inflammation and predicted that greater changes in [Ca2+]i signaling would be seen in synovial fluid (SF) T cells. We also examined the mechanisms underlying the altered [Ca2+]i signals.
Paired PB and SF T cells from patients with chronic inflammatory arthritis were stimulated with mitogen to assess the magnitude of the [Ca2+]i signal in cell populations by fluorometry, the pattern of the [Ca2+]i signal in individual cells in a single-cell ion-imaging system, and the spatial distribution of Ca2+ within intracellular organelles.
There was a significantly smaller [Ca2+]i signal after phytohemagglutinin protein stimulation of SF T cells (peak rise in [Ca2+]i signal PB versus SF 200 nM versus 180 nM; P < 0.05). In single SF T cells, a change in the pattern of the [Ca2+]i signal and a reduction in the number of responding cells was seen. These changes were a magnification of those seen in RA PB compared with control PB T cells. The contribution of Ca2+ release from intracellular stores to the final [Ca2+]i signal in PB and SF T cells was equal, but there was a significant increase in the Ca2+ remaining in the endoplasmic reticulum (ER) in SF T cells after TCR activation (PB versus SF 6 nM versus 19 nM; P < 0.05). Non-ER Ca2+ stores were not similarly affected.
We found abnormalities in the magnitude, pattern, and spatial distribution of [Ca2+]i signaling in T cells from SF of patients with chronic inflammatory arthritis. A reduction in the number of responding SF T cells may partly explain some of our observations. However, we propose that the observed redistribution of SF Ca2+ stores may underlie the altered [Ca2+]i signaling, thus making these cells hyporesponsive to mitogen. The inflammatory environment of the joint and the late stage of differentiation of SF T cells are both likely to contribute to these changes in [Ca2+]i signaling, resulting in aberrant T cell function and promotion of disease chronicity.
类风湿关节炎（RA）患者的外周血（PB）T细胞对有丝分裂原的增殖能力较差，这种变化与T细胞受体（TCR）刺激后细胞内Ca2+（[Ca2+]i）信号传导减少有关。我们推测，这部分是由于炎症介质的作用，并预测滑膜液（SF）T细胞中[Ca2+]i信号传导的变化会更大。我们还研究了[Ca2+]i信号改变的潜在机制。
用有丝分裂原刺激慢性炎症性关节炎患者的配对PB和SF T细胞，通过荧光测定法评估细胞群体中[Ca2+]i信号的强度，在单细胞离子成像系统中评估单个细胞中[Ca2+]i信号的模式，以及细胞内细胞器中Ca2+的空间分布。
植物血凝素蛋白刺激SF T细胞后，[Ca2+]i信号明显较小（[Ca2+]i信号的峰值升高PB对SF为200 nM对180 nM；P<0.05）。在单个SF T细胞中，观察到[Ca2+]i信号模式的变化和反应细胞数量的减少。与对照PB T细胞相比，这些变化是RA PB中所见变化的放大。细胞内储存库中Ca2+释放对PB和SF T细胞最终[Ca2+]i信号的贡献相等，但TCR激活后SF T细胞内质网（ER）中残留的Ca2+显著增加（PB对SF为6 nM对19 nM；P<0.05）。非ER Ca2+储存库未受到类似影响。
我们发现慢性炎症性关节炎患者SF中T细胞的[Ca2+]i信号传导在强度、模式和空间分布上存在异常。反应性SF T细胞数量的减少可能部分解释了我们的一些观察结果。然而，我们认为观察到的SF Ca2+储存库的重新分布可能是[Ca2+]i信号改变的基础，从而使这些细胞对有丝分裂原反应低下。关节的炎症环境和SF T细胞的晚期分化都可能导致[Ca2+]i信号的这些变化，从而导致T细胞功能异常并促进疾病慢性化。
